I know older games used these rasterization "tricks" to have shadows and reflections without ray tracing. Looking back, I remember an old 'easter-egg'/mistake in a spiderman videogame, where the reflection of the twin towers could supposedly be seen in the reflection of a building but the building did not exist in the physical game. KNowing what I know now, it makes sense that this was a left over/misplaced reflection texture that was being used to fake the reflection. If ray tracing was implemented this sort-of bug wouldn't have existed.
Also after implementing task 4 in P3, I could see that maybe shadows with ray tracing in scenes with few light sources, may have been on the easier side as far as computation goes. I wonder if games/animations ever used hybrid methods in which shadows were ray traced and the rest was rasterized?
That's a very good question! I think it could be hard to combine these two methods because it could be tricky to deal with the boundary case (e.g. local use of rasterization and global use of ray tracing)
Modern games and graphics (the newest RTX 20x series) are supporting raytracing recently, so is this actually a very new topic and field to be developed? I found ray tracing a very advanced technology when those corporations introduce their new products.